Method for preparing anti-tumor medicine imatinib

The invention relates to a method for preparing an anti-tumor medicine imatinib, which comprises the following steps of: performing amidation-condensation two-step 'one pot' reaction on 4-methyl-3-bromaniline (V), 4-(chloromethyl) benzoyl chloride (IV) and N-methyl piperazine to directly obtain a key intermediate N-(4-methyl-3-bromophenyl)-4-(4-methyl piperazin-1-methyl)-benzamide (III); and performing nucleophilic substitution on the N-(4-methyl-3-bromophenyl)-4-(4-methyl piperazin-1-methyl)-benzamide (III) and 4-(3-Pyridinyl)-2-aminopyrimidine (II) to obtain the imatinib (I). The method hasthe advantages that: the process is reasonably designed, expensive reagents are not used, the reaction yield is high, raw materials are low in cost, the operation is simple and convenient, rigorous reaction conditions are absent, and the method is suitable for mass production.